LIGO Hanford Observatory

arranged in the shape of an L with 2.5-mile (4-kilometer) arms. Since gravitational waves penetrate the earth unimpeded, these installations don't need exposure to the sky and remain entirely shielded in a concrete cover. At the vertex of the L, and at the end of each of its arms, hang test masses from wires, and the masses possess mirror surfaces. These mirrors make up the sensors of gravitational waves. Two facilities, thousands of miles apart, will eliminate uncertainty in the results. Less «

Aerial View of LIGO Livingston Laboratory

Credit: LIGO Laboratory

Certain detection of gravitational waves requires at least two detectors located at widely separated sites. Regional phenomena such as micro-earthquakes,…Read More »

acoustic noise, and laser fluctuations can cause disturbances that simulate a gravitational wave event, but do not seem likely to happen simultaneously at two distant sites. Settings for the LIGO observatories were selected by the National Science Foundation (NSF) near Livingston, Louisiana, and at Hanford, Washington. These venues, separated by nearly 2,000 miles, possess the size and flatness sufficient to accommodate the 2.5-mile (4-kilometer) interferometer arms. Less «

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Livingston Vertex Area #2

Credit: LIGO Laboratory

Livingston vertex area showing the intersection point of the two arms.

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Livingston Vertex Area

Credit: LIGO Laboratory

Large gate valves are visible above the beam pipes to either side of the chambers.

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HAM from the Inside

Credit: LIGO Laboratory

HAM (Horizontal Access Module) is a vacuum chamber holding the input and output optics that inject laser light into the main LIGO interferometer, and further…Read More »